Base station apparatus, mobile station apparatus, method for mapping a response signal, and method for determining a response signal resource

ABSTRACT

A mobile station comprises a receiver and a processor. The receiver is configured to receive, from a base station, allocation information indicating one or a plurality of allocated resource block(s) of uplink which are consecutive in a frequency domain. The processor is configured to determine, based on the allocation information, one of the resources of downlink, to which an ACK or NACK signal is distributively mapped onto a plurality of resource elements in subcarrier groups. The subcarrier resources within subcarrier group are consecutive in frequency domain and nonconsecutive in the frequency domain among subcarrier groups.

This application is a continuation of U.S. patent application Ser. No.15/097,560 filed Apr. 13, 2016, now granted as U.S. Pat. No. 10,652,920,which is a continuation of U.S. patent application Ser. No. 14/250,301,filed Apr. 10, 2014, now granted as U.S. Pat. No. 9,485,781, which is acontinuation of U.S. patent application Ser. No. 13/470,106, filed May11, 2012, now granted as U.S. Pat. No. 8,705,476, which is acontinuation of U.S. patent application Ser. No. 13/271,942, filed Oct.12, 2011, now granted as U.S. Pat. No. 8,200,237, which is acontinuation of U.S. patent application Ser. No. 12/983,770 filed Jan.3, 2011, now granted as U.S. Pat. No. 8,064,919, which is a continuationof U.S. patent application Ser. No. 12/532,352 filed Sep. 21, 2009, nowgranted as U.S. Pat. No. 7,941,153, which is a national stage ofPCT/JP2008/000675 filed Mar. 21, 2008, which claims priority of JapaneseApplication No. 2007-077502 filed Mar. 23, 2007; Japanese ApplicationNo. 2007-420853 filed May 1, 2007; and Japanese Application No.2007-211104 filed Aug. 13, 2007, the entire contents of each which areincorporated by reference herein.

TECHNICAL FIELD

The present invention relates to a radio communication base stationapparatus and control channel mapping method.

BACKGROUND ART

In mobile communication, ARQ (Automatic Repeat reQuest) is applied touplink data transmitted from a radio communication mobile stationapparatus (hereinafter simply “mobile station”) to a radio communicationbase station apparatus (hereinafter simply “base station”) in uplink,and a response signal showing uplink data error detection result is fedback to the mobile station in downlink. The base station performs a CRC(Cyclic Redundancy Check) for the uplink data, and, if CRC=OK (noerror), an ACK (Acknowledgment) signal is fed back, and, if CRC=NG(error), a NACK (Negative Acknowledgment) signal is fed back as aresponse signal to the mobile station.

To use downlink communication resources efficiently, studies areconducted recently about ARQ, which associates uplink resource blocks(RBs) for transmitting uplink data and downlink control channels fortransmitting response signals in downlink (e.g. see Non-patent Document1). By this means, a mobile station is able to identify control channelsin which a response signal is transmitted to the mobile stationaccording to RB allocation information reported from the base stationeven when allocation information about the control channel is notreported separately.

Further, studies are conduct for ARQ recently whereby a response signalis spread and the spread response signal is duplicated in order toaverage interference of the response signal from neighboring cells orsectors and provide frequency diversity gain for the response signal(e.g. see Non-patent Document 2).

Non-patent Document 1: 3GPP RAN WG1 Meeting document, R1-070932,“Assignment of Downlink ACK/NACK Channel,” Panasonic, February 2007

Non-patent Document 2: 3GPP RAN WG1 Meeting document, R1-070734,“ACK/NACK Channel Transmission in E-UTRA Downlink,” TI, February 2007

DISCLOSURE OF INVENTION Problems to be Solved by the Invention

It is possible to use the above ARQs studied recently by combining them.Now, a specific example to map response signals to downlink controlchannels will be explained. With the following explanation, a basestation receives uplink data transmitted from mobile stations usinguplink RB #1 to RB #8 shown in FIG. 1, and the base station mapsresponse signals to uplink data (ACK signals and NACK signals) todownlink control channels CH #1 to CH #8, mapped in four frequencybands, subcarriers f1 to f4, f9 to f12, f17 to f20 and f25 to f28 shownin FIG. 2, and transmits the response signals to the mobile stations.Further, the base station spreads a response signal with spreading codehaving spreading factor 4, and repeats the spread response signal withrepetition factor 2. Therefore, as shown in FIG. 2, downlink controlchannels CH #1 to CH #4 are mapped to identical bands, subcarriers f1 tof4 and f17 to f20 in a localized manner, and downlink control channelsCH #5 to CH #8 are mapped to identical bands, subcarriers f9 to f12 andf25 to f28 in a localized manner.

Further, as shown in FIG. 3, the uplink RBs shown in FIG. 1 and thedownlink control channels shown in FIG. 2 are associated one by one.Therefore, as shown in FIG. 3, a response signal to uplink datatransmitted using RB #1 shown in FIG. 1 is mapped to downlink controlchannel CH #1, that is, mapped to subcarriers f1 to f4 and f17 to f20shown in FIG. 2. Likewise, as shown in FIG. 3, a response signal touplink data transmitted using RB #2 shown in FIG. 1 is mapped todownlink control channel CH #2, that is, mapped to subcarriers f1 to f4and f17 to f20 shown in FIG. 2. The same applies to RB #3 to RB #8.

Further, when a coding block is formed with a plurality of consecutiveRBs on the frequency domain and RBs are allocated in one-block units,the base station transmits response signals to mobile stations bymapping response signals to a plurality of downlink control channels inassociation with a plurality of uplink RBs included in one coding block.For example, when one coding block is formed with three consecutiveuplink RBs, RB #1 to RB #3, amongst uplink RB #1 to RB #8 shown in FIG.1, the base station maps code-multiplexed spread response signals todownlink control channels CH #1 to CH #3 mapped in a localized manner inidentical bands, subcarriers f1 to f4 and f17 to f20 shown in FIG. 2.

Although downlink control channels CH #1 to CH #8 are mapped to sixteensubcarriers, subcarriers f1 to f4, f9 to f12, f17 to f20 and f25 to f28in this way, with the above example, response signals are mapped only toeight subcarriers, subcarriers f1 to f4 and f17 to f20. That is, withthe above example, response signals are only mapped to half of allsubcarriers to which downlink control channels are mapped.

In the case where downlink control channels mapped in the limitedfrequency domain are used in this way, little frequency diversity effectmay be obtained depending upon the positions to which downlink controlchannels are mapped.

It is therefore an object of the present invention to provide a basestation and control channel mapping method that can maximize thefrequency diversity effect on downlink control channels.

Means for Solving the Problems

The base station of the present invention adopts a configurationincluding: an allocation section that allocates a first control channelformed with a plurality of consecutive RBs or a plurality of CCEs to aradio communication mobile station apparatus; and a mapping section thatmaps control signals for the radio communication mobile stationapparatus to a plurality of second control channels mapped in adistributed manner on a frequency domain in association with theplurality of RBs or the plurality of CCEs.

Advantageous Effect of the Invention

According to the present invention, it is possible to maximize thefrequency diversity effect on downlink control channels.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an uplink RB mapping example;

FIG. 2 illustrates a mapping example of downlink control channels;

FIG. 3 shows the associations between uplink RBs and downlink controlchannels;

FIG. 4 is a block diagram showing the configuration of the base stationaccording to Embodiment 1 of the present invention;

FIG. 5 is a block diagram showing the configuration of the mobilestation according to Embodiment 1 of the present invention;

FIG. 6 illustrates the downlink control channel mapping according toEmbodiment 1 of the present invention;

FIG. 7 illustrates the downlink control channel mapping according toEmbodiment 2 of the present invention;

FIG. 8 illustrates the downlink control channel mapping in cell 2,according to Embodiment 3 of the present invention;

FIG. 9 shows the associations between SCCHs and downlink CCEs accordingto Embodiment 4 of the present invention;

FIG. 10 illustrates the downlink CCE mapping example according toEmbodiment 4 of the present invention;

FIG. 11 shows the associations between downlink CCEs and downlinkcontrol channels according to Embodiment 4 of the present invention;

FIG. 12 is a block diagram showing the configuration of the base stationaccording to Embodiment 4 of the present invention;

FIG. 13 is a block diagram showing the configuration of the mobilestation according to Embodiment 4 of the present invention;

FIG. 14 shows the associations (variations) between SCCHs and downlinkCCEs, according to Embodiment 4 of the present invention;

FIG. 15 illustrates the downlink control channel mapping according toEmbodiment 4 of the present invention;

FIG. 16 illustrates downlink CCEs used in the number of OFDMs formultiplexing according to Embodiment 5 of the present invention;

FIG. 17 is a block diagram showing the configuration of the base stationaccording to Embodiment 5 of the present invention;

FIG. 18A illustrates the physical resources (the number of OFDMs formultiplexing: 1), according to Embodiment 5 of the present invention;

FIG. 18B illustrates the physical resources (the number of OFDMs formultiplexing: 2), according to Embodiment 5 of the present invention;

FIG. 19 is a block diagram showing the configuration of the mobilestation according to Embodiment 5 of the present invention;

FIG. 20 illustrates the downlink control channel mapping according toEmbodiment 5 of the present invention;

FIG. 21 illustrates another downlink control channel mapping (example1); and

FIG. 22 illustrates another downlink control channel mapping (example2).

BEST MODE FOR CARRYING OUT THE INVENTION

Now, embodiments of the present invention will be described in detailwith reference to the accompanying drawings. The base station accordingto the present embodiment of the present invention transmits a responsesignal using the OFDM scheme. Further, the mobile station according tothe present embodiment transmits uplink data by DFTs-FDMA (DiscreteFourier Transform spread Frequency Division Multiple Access). Whenuplink data is transmitted by DFTs-FDMA, as described above, a codingblock is formed with a plurality of consecutive RBs on the frequencyaxis (in the frequency domain), and the base station allocates RBs tomobile stations in one-block units.

Embodiment 1

FIG. 4 shows the configuration of base station 100 according to thepresent embodiment, and FIG. 5 shows the configuration of mobile station200 according to the present embodiment.

To avoid complex explanation, FIG. 4 shows components that pertain touplink data reception and downlink transmission of response signals touplink data, which the present invention closely relates to, anddrawings and explanations of components that pertain to downlink datatransmission are omitted. Similarly, FIG. 5 shows components thatpertain to uplink data transmission and downlink reception of responsesignals to uplink data, which the present invention closely relates to,and drawings and explanations of components that pertain to downlinkdata reception are omitted.

In base station 100 in FIG. 4, RB allocation section 101 allocatesuplink RBs to mobile stations by frequency scheduling and generates RBallocation information showing which uplink RBs are allocated to whichmobile stations (i.e. allocation information showing RB allocationresults), and outputs the generated RB allocation information toencoding section 102 and mapping section 109. Further, RB allocationsection 101 allocates RBs using a plurality of consecutive RBs includedin one coding block, as one unit. An RB is formed by grouping into ablock a number of subcarriers neighboring each other at intervals ofcoherence bandwidth.

Encoding section 102 encodes the RB allocation information, and outputsthe encoded RB allocation information to modulation section 103.

Modulation section 103 modulates the encoded RB allocation information,to generate RB allocation information symbols, and outputs the RBallocation information symbols to S/P section (serial-to-parallelconversion section) 104.

S/P section 104 converts the RB allocation information symbols receivedas input from modulation section 103 in series into parallel RBallocation information symbols, and outputs the parallel RB allocationinformation symbols to mapping section 109.

Modulation section 105 modulates a response signal received as inputfrom CRC section 117 and outputs the modulated response signal tospreading section 106.

Spreading section 106 spreads the response signal received as input frommodulation section 105 and outputs the spread response signal torepetition section 107.

Repetition section 107 duplicates (repeats) the response signal receivedas input from spreading section 106 and outputs a plurality of responsesignals including identical response signals, to S/P section 108.

S/P section 108 converts the response signals received as input fromrepetition section 107 in series into parallel response signals, andoutputs the parallel response signals to mapping section 109.

Mapping section 109 maps the RB allocation information symbols andresponse signals to a plurality of subcarriers forming an OFDM symbol,and outputs the mapped RB allocation information symbols and responsesignals to IFFT (Inverse Fast Fourier Transform) section 110. Here,based on the RB allocation information received as input from RBallocation section 101, mapping section 109 maps the response signals todownlink control channels mapped on the frequency domain in associationwith uplink RBs. For example, when mapping section 109 receives RB #1 toRB #3 shown in FIG. 1 from RB allocation section 101 as RB allocationinformation for mobile station 200, as shown in FIG. 3, mapping section109 maps response signals to uplink data transmitted from mobile station200 using RB #1 to RB #3, to downlink control channels CH #1 to CH #3.The mapping processing in mapping section 109 will be described later indetail.

IFFT section 110 performs an IFFT on the RB allocation informationsymbols and response signals mapped to a plurality of subcarriers, togenerate an OFDM symbol, and outputs the generated OFDM symbol to CP(Cyclic Prefix) addition section 111.

CP addition section 111 adds the same signal as the tail part of theOFDM symbol, as a CP, to the head of the OFDM symbol.

Radio transmitting section 112 performs transmitting processingincluding D/A conversion, amplification and up-conversion, on the OFDMsymbol with a CP, and transmits the OFDM symbol with a CP aftertransmitting processing, from antenna 113, to mobile station 200.

Meanwhile, radio receiving section 114 receives uplink data transmittedfrom mobile station 200 via antenna 113, and performs receivingprocessing including down-conversion and A/D conversion for this uplinkdata.

Demodulation section 115 demodulates the uplink data and outputs thedemodulated uplink data to decoding section 116.

Decoding section 116 decodes the demodulated uplink data, and outputsthe decoded uplink data to CRC section 117.

CRC section 117 performs error detection for the uplink data after thedecoding using CRC, to generate, as a response signal, an ACK signal ifCRC=OK (no error) or a NACK signal if CRC=NG (error), and outputs thegenerated response signal to modulation section 105. Further, if CRC=OK(no error), CRC section 117 outputs the uplink data after decoding asreceived data.

Meanwhile, in mobile station 200 shown in FIG. 5, radio receivingsection 202 receives an OFDM symbol transmitted from base station 100via antenna 201, and performs receiving processing includingdown-conversion and A/D conversion on this OFDM symbol.

CP removing section 203 removes the CP from the OFDM symbol afterreceiving processing.

FFT (Fast Fourier Transform) section 204 performs an FFT on the OFDMsymbol after CP removal, to acquire RB allocation information symbolsand response signals, and outputs them to demultiplexing section 205.

Demultiplexing section 205 demultiplexes the input signals into the RBallocation information symbols and the response signals, and outputs theRB allocation information symbols to P/S section 206 and the responsesignals to P/S section 210. Here, based on the specified result receivedas input from mapping specifying section 209, demultiplexing section 205demultiplexes response signals from the input signal.

P/S section 206 converts a plurality of parallel RB allocationinformation symbols received as input from demultiplexing section 205into RB allocation information symbols in series, and outputs the RBallocation information symbols in series to demodulation section 207.

Demodulation section 207 demodulates the RB allocation informationsymbols, and outputs the demodulated RB allocation information todecoding section 208.

Decoding section 208 decodes the demodulated RB allocation information,and outputs the decoded RB allocation information to transmissioncontrol section 214 and mapping specifying section 209.

Based on the RB allocation information received as input from decodingsection 208, mapping specifying section 209 specifies downlink controlchannels to which response signals to uplink data transmitted from themobile station are mapped. For example, when the RB allocationinformation for a mobile station is RB #1 to RB #3 shown in FIG. 1, asshown in FIG. 3, mapping specifying section 209 specifies CH #1 to CH #3to be downlink control channels for the mobile station to which theresponse signals are mapped. Then mapping specifying section 209 outputsthe specified result to demultiplexing section 205. The specifyingprocessing in mapping specifying section 209 will be described later indetail.

P/S section 210 converts the parallel response signals received as inputfrom demultiplexing section 205 into in series, and outputs the responsesignals in series to despreading section 211.

Despreading section 211 despreads the responses signals, and outputs thedespread response signals to combining section 212.

In the despread response signals, combining section 212 combines theoriginal response signal and the response signals generated by repeatingthe original response signal, and outputs the response signal after thecombining to demodulation section 213.

Demodulation section 213 demodulates the response signal aftercombining, and outputs the demodulated response signal to retransmissioncontrol section 216.

When RB allocation information received as input from decoding section208 shows that uplink RBs are allocated to the subject mobile station,transmission control section 214 maps the transmission data to the RBsdesignated in the RB allocation information, and outputs the mappedtransmission data to encoding section 215.

Encoding section 215 encodes the transmission data, and outputs theencoded transmission data to retransmission control section 216.

Upon initial transmission, retransmission control section 216 holds theencoded transmission data and outputs it to modulation section 217.Retransmission control section 216 holds the transmission data untilretransmission control section 216 receives an ACK signal fromdemodulation section 213. Further, when a NACK signal is received asinput from demodulation section 213, that is, upon retransmission,retransmission control section 216 outputs the transmission data that isheld, to modulation section 217.

Modulation section 217 modulates the encoded transmission data, receivedas input from retransmission control section 216, and outputs themodulated transmission data to radio transmitting section 218.

Radio transmitting section 218 performs transmitting processingincluding D/A conversion, amplification and up-conversion on themodulated transmission data, and transmits the transmission data aftertransmitting processing from antenna 201 to base station 100. The datatransmitted in this way becomes uplink data.

Next, the mapping processing in mapping section 109 in base station 100and the specifying processing in mapping specifying section 209 inmobile station 200 will be explained in detail.

With the present embodiment, base station 100 receives uplink datatransmitted from mobile station 200 using RB #1 to RB #8 shown in FIG.1, and base station 100 maps response signals to uplink data (ACKsignals and NACK signals) to CH #1 to CH #8, mapped in four frequencybands, subcarriers f1 to f4, f9 to f12, f17 to f20 and f25 to f28 shownin FIG. 6, and transmits the response signals to mobile station 200.Further, similar to FIG. 2, spreading section 106 in base station 100spreads the response signal with spreading code having spreading factor4, and repetition section 107 repeats the spread response signal withrepetition factor 2. Further, as shown in FIG. 3, the uplink RBs shownin FIG. 1 and the downlink control channels shown in FIG. 6 areassociated one by one.

Mapping section 109 maps response signals for mobile station 200 to aplurality of downlink control channels that are associated with aplurality of RBs and that are subject to distributed mapping on thefrequency domain. Mapping section 109 holds association informationbetween uplink RBs and downlink control channels in FIG. 3, and thedownlink control channel mapping information shown in FIG. 6, and, basedon these, maps the response signals to subcarriers to which downlinkcontrol channels are mapped.

To be more specific, when the RB allocation information for mobilestation 200 designates RB #1 to RB #3, mapping section 109 maps theresponse signals to CH #1 associated with RB #1 in FIG. 3, that is, mapsthe response signals to subcarriers f1 to f4 and f17 to f20 shown inFIG. 6. Likewise, mapping section 109 maps the response signals to CH #2associated with RB #2, that is, maps the response signals to subcarriersf9 to f12 and subcarriers f25 to f28, and maps the response signals toCH #3 associated with RB #3, that is, maps the response signals tosubcarriers f1 to f4 and subcarriers f17 to f20.

Here, in the downlink control channel mapping shown in FIG. 6, downlinkcontrol channels (e.g. CH #1 and CH #2) associated with the twoconsecutive uplink RBs in FIG. 1 (e.g. RB #1 and RB #2) are mapped todifferent frequency bands in a distributed manner. In other words, thedownlink control channels mapped in a localized manner in identicalbands in FIG. 6 correspond to a plurality of nonconsecutive uplink RBsat two-RB intervals in FIG. 1. To be more specific, for example,downlink control channels mapped to subcarriers f1 to f4 shown in FIG. 6in a localized manner are downlink control channels CH #1, CH #3, CH #5and CH #7, and the uplink RBs associated with those downlink controlchannels are nonconsecutive RBs at two-RB intervals, RB #1, RB #3, RB #5and RB #7, as shown in FIG. 3.

Consequently, when base station 100 transmits response signals to uplinkdata transmitted from mobile station 200, using a plurality ofconsecutive uplink RBs, it is possible to prevent response signals frombeing mapped concentrated in identical bands. That is, base station 100is able to map response signals over a plurality of frequency bands in adistributed manner, to transmit the response signals subject todistributed mapping. For example, as described above, when the RBallocation information for mobile station 200 designates RB #1 to RB #3,mapping section 109 maps the response signals to subcarriers f1 to f4and f17 to f20 shown in FIG. 6, the response signals to subcarriers f9to f12 and f25 to f28, and, the response signals to subcarriers f1 to f4and f17 to f20. By this means, the response signals are mapped to allsubcarriers f1 to f4, f9 to f12, f17 to f20 and f25 to f28 uniformly ina distributed manner to which downlink control channels are mapped.

In this way, mapping section 109 maps response signals to downlinkcontrol channels based on the associations between uplink RBs anddownlink control channels shown in FIG. 3 and the downlink controlchannel mapping shown in FIG. 6, so that radio transmitting section 112in base station 100 is able to transmit response signals to mobilestation 200 using downlink control channels that are associated withuplink RBs and that are mapped in a distributed manner on the frequencydomain.

Likewise, mapping specifying section 209 in mobile station 200 (FIG. 5)holds the association information between uplink RBs and downlinkcontrol channels shown in FIG. 3 and the downlink control channelmapping information shown in FIG. 6, and specifies the downlink controlchannels to which response signals for the mobile station are mapped,from the RB allocation information received. To be more specific, whenmapping specifying section 209 receives as input RB allocationinformation showing that RB #1 to RB #3 shown in FIG. 1 are allocated toa mobile station from decoding section 208, based on the associationsshown in FIG. 3, mapping specifying section 209 specifies that theresponse signals for the mobile station are mapped to subcarriers f1 tof4 and f17 to f20, to which downlink control channels CH #1 and CH #3are mapped, and to subcarriers f9 to f12 and f25 to f28, to whichdownlink control channel CH #2 is mapped, as shown in FIG. 6.

In this way, according to the present embodiment, it is less likely thatresponse signals to uplink data, which are transmitted using a pluralityof consecutive uplink RBs, concentrate in identical frequency bands andcode-multiplexed, so that it is possible to map response signals in adistributed manner on the frequency domain. Therefore, according to thepresent embodiment, it is possible to maximize the frequency diversityeffect on downlink control channels.

Embodiment 2

By mapping spread blocks generated by spreading response signals toconsecutive subcarriers (e.g. subcarriers f1 to f4 shown in FIG. 6) asin Embodiment 1, intersymbol interference (ISI) that is caused betweenneighboring subcarriers decreases to an extent ISI can be ignored.

However, if base station 100 controls transmission power on a perdownlink control channel basis, it is no longer possible to ignore ISIbecause transmission power varies between a plurality of downlinkcontrol channels mapped in identical frequency bands and ISI from adownlink control channel of greater transmission power to a downlinkcontrol channel of smaller transmission power increases. For example,focusing upon downlink control channels CH #1 and CH #3 shown in FIG. 6,if the transmission power for downlink control channel CH #1 is greaterthan transmission power for downlink control channel CH #3, downlinkcontrol channels CH #1 and CH #3 are mapped to identical frequencybands, subcarriers f1 to f4 and f17 to f20, and therefore ISI fromdownlink control channel CH #1 to downlink control channel CH #3 iscaused in both frequency bands.

Then, mapping section 109 according to the present embodiment, mapsresponse signals to a plurality of downlink control channels indifferent mapping patterns in a distributed manner on the frequencydomain.

That is, in FIG. 6, downlink control channels CH #1 and CH #3 are mappedto subcarriers f1 to f4 and f17 to f20 in identical mapping patterns. Bycontrast with this, with the present embodiment, as shown in FIG. 7, themapping pattern of downlink control channel CH #1 and the mappingpattern in downlink control channel CH #3 vary, and, downlink controlchannel CH #1 is mapped to subcarriers f1 to f4 and f17 to f20 anddownlink control channel CH #3 is mapped to subcarriers f1 to f4 and f9to f12. That is, with the present embodiment, as shown in FIG. 7,downlink control channels CH #1 and CH #3 are mapped to identicalsubcarriers f1 to f4, and meanwhile, downlink control channel CH #1 ismapped to subcarriers f17 to f20 and downlink control channel CH #3 ismapped to subcarriers f9 to f12. That is, CH #1 and CH #3 are mapped indifferent mapping patterns in a distributed manner on the frequencydomain.

By this means, similar to Embodiment 1, when mapping section 109 mapsresponse signals to uplink data transmitted using RB #1 to RB #3, todownlink control channels CH #1 to CH #3, ISI is not caused in the bothfrequency bands, subcarriers f9 to f12 and subcarriers f17 to f20 thoughISI is caused in subcarriers f1 to f4 between downlink control channelCH #1 of greater transmission power and downlink control channel CH #3of smaller transmission power.

In this way, according to the present embodiment, it is possible toprovide the same advantage as in Embodiment 1, and it is possible toreduce ISI by randomizing ISI caused by transmission power control.

By mapping downlink control channels CH #1 to CH #8 on a random basis onthe frequency domain, it is possible to map downlink control channels CH#1 to CH #8 in different mapping patterns in a distributed manner on thefrequency domain.

Embodiment 3

With the present embodiment, response signals are mapped to a pluralityof downlink control channels adopting different mapping patterns betweenneighboring cells.

Here, a case will be explained where a cell neighboring cell 1 is onecell, cell 2. Further, cell 1 and cell 2 are synchronized. Further, whenFIG. 6 shows a downlink control channel mapping pattern in cell 1, FIG.8 shows a downlink control channel mapping pattern in cell 2. Further,similar to Embodiment 1, the downlink control channels shown in FIG. 8are mapped in a distributed manner on the frequency domain inassociation with a plurality of consecutive uplink RBs.

The downlink control channels mapped in identical frequency bands varybetween the mapping pattern in cell 1 (FIG. 6) and the mapping patternin cell 2 (FIG. 8). That is, the identical downlink control channels aremapped to different frequency bands in a distributed manner in cell 1and cell 2.

To be more specific, in cell 1, as shown in FIG. 6, downlink controlchannels CH #1, CH #3, CH #5 and CH #7 are mapped to subcarriers f1 tof4 and f17 to f20, and downlink control channels CH #2, CH #4, CH #6 andCH #8 are mapped to subcarriers f9 to f12 and f25 to f28. By contrastwith this, in cell 2, as shown in FIG. 8, downlink control channels CH#2, CH #4, CH #6 and CH #8 are mapped to subcarriers f1 to f4 and f17 tof20, and downlink control channels CH #1, CH #3, CH #5 and CH #7 aremapped to subcarriers f9 to f12 and f25 to f28.

In this way, according to the present embodiment, mapping patterns ofdownlink control channels CH #1 to CH #8 on the frequency domain aremade different between neighboring cells. Therefore, according to thepresent embodiment, it is possible to provide the same advantage as inEmbodiment 1 in the same cell, and, when response signals aretransmitted at the same time in neighboring cells, it is possible toreduce inter-cell interference by randomizing inter-cell interferencefrom neighboring cells between downlink control channels.

Although a case has been explained above with the present embodimentwhere the present invention is implemented between neighboring cells,the present invention may also be implemented between neighboringsectors in the same cell. That is, in the above explanation, byregarding cell 1 as sector 1 and cell 2 as sector 2, the presentinvention may also be implemented between neighboring sectors. Further,it is not necessary to take into consideration of the synchronizationbetween neighboring sectors, so that the present invention may beimplemented easier between neighboring sectors than between neighboringcells.

Further, although a case has been explained above with an example wherethe number of cells is two, the present invention may also beimplemented where the number of cells is three or more.

Embodiment 4

With the present embodiment, a case will be explained where CCEs(Control Channel Elements) and downlink control channels fortransmitting response signals in downlink, are associated.

With the present embodiment, a case will be explained where CCEs(Control Channel Elements) and downlink control channels fortransmitting response signals in downlink, are associated.

Further, the base station allocates a plurality of SCCHs to mobilestations and transmits SCCH allocation information showing which SCCHsin a plurality of SCCHs are assigned to which mobile stations (i.e.allocation information showing SCCH allocation results), to the mobilestations before transmitting the RB allocation information.

Further, each SCCH is formed with one CCE or a plurality of CCEs. Forexample, SCCH #1 to SCCH #8 adopt the configurations shown in FIG. 9.That is, SCCH #1 is formed with CCE #1 and CCE #2, SCCH #2 is formedwith CCE #3 and CCE #4, SCCH #3 is formed with CCE #5 and CCE #6, SCCH#4 is formed with CCE #7 and CCE #8, SCCH #5 is formed with CCE #1 toCCE #4, and SCCH #6 is formed with CCE #5 to CCE #8. In this way, whenone SCCH is formed with a plurality of CCEs, one SCCH is formed with aplurality of consecutive CCEs.

CCE #1 to CCE #8 and physical resources on the frequency axis (in thefrequency domain) are associated as shown in FIG. 10, for example. Thatis, one CCE is associated with a plurality of physical resources mappedon the frequency domain in a distributed manner.

Here, to use downlink communication resources efficiently, it is onepossibility to associate CCEs and downlink control channels fortransmitting response signals in downlink, and identify the controlchannels in which response signals are transmitted to a mobile stationbased on SCCH allocation information the base station reports to themobile station. For example, as shown in FIG. 11, the CCEs shown in FIG.9 and the downlink control channels shown in FIG. 2 are associated oneby one. Therefore, as shown in FIG. 11, response signals to uplink datafrom the mobile station allocated SCCH #1 shown in FIG. 9 are mapped todownlink control channels CH #1 and CH #2, that is, mapped tosubcarriers f1 to f4 and f17 to f20 shown in FIG. 2. Likewise, as shownin FIG. 11, response signals to uplink data from the mobile stationallocated SCCH #2 shown in FIG. 9 are mapped to downlink controlchannels CH #3 and CH #4, that is, to subcarriers f1 to f4 and f17 tof20 shown in FIG. 2. The same applies to SCCH #3 to SCCH #6.

Although downlink control channels CH #1 to CH #8 are mapped to sixteensubcarriers, subcarriers f1 to f4, f9 to f12, f17 to f20 and f25 to f28in this way, with the above example, response signals are mapped only toeight subcarriers, subcarriers f1 to f4 and f17 to f20. That is, withthe above example, response signals are only mapped to half of allsubcarriers to which downlink control channels are mapped.

Therefore, even when CCE #1 to CCE #8 in downlink with downlink controlchannels CH #1 to CH #8 are associated one by one as shown in FIG. 11,similar to the case where uplink RB # 1 to RB #8 and downlink controlchannels CH #1 to CH #8 are associated one by one as shown in FIG. 3,little frequency diversity effect may be obtained depending upon thepositions to which downlink control channels are mapped.

Then, with the present embodiment, when downlink CCE #1 to CCE #8 anddownlink control channels CH #1 to CH #8 are associated, the mapping ofdownlink control channels CH #1 to CH #8 is shown in FIG. 6 (Embodiment1).

FIG. 12 shows the configuration of base station 300 according to thepresent embodiment, and FIG. 13 shows the configuration of mobilestation 400 according to the present embodiment. In FIG. 12, the samereference numerals are assigned to the same components in FIG. 4(Embodiment 1), and description thereof will be omitted. Further, inFIG. 13, the same reference numerals are assigned to the same componentsin FIG. 5 (Embodiment 1), and description thereof will be omitted.

In base station 300 shown in FIG. 12, SCCH allocation section 301allocates SCCH #1 to SCCH #8 to mobile stations, generates SCCHallocation information, and outputs the SCCH allocation information toencoding section 302 and mapping section 305.

Encoding section 302 encodes the SCCH allocation information, andoutputs the encoded SCCH allocation information to modulation section303.

Modulation section 303 modulates the encoded SCCH allocationinformation, to generate SCCH allocation information symbols, andoutputs the SCCH allocation information symbols to S/P section 304.

S/P section 304 converts the SCCH allocation information symbolsreceived as input from modulation section 303 in series into parallelSCCH allocation information symbols, and outputs the parallel SCCHallocation information symbols to mapping section 305.

Mapping section 305 maps the SCCH allocation information symbols, the RBallocation information symbols and response signals to a plurality ofsubcarriers forming an OFDM symbol, and outputs the mapped SCCHallocation information symbols, RB allocation information symbols andresponse signals to IFFT section 306.

Here, based on the SCCH allocation information received as input fromSCCH allocation section 301, mapping section 305 maps the responsesignals to downlink control channels mapped on the frequency domain inassociation with CCEs. For example, when mapping section 305 receivesSCCH #1 shown in FIG. 9 from SCCH allocation section 301 as the SCCHallocation information for mobile station 400, as shown in FIG. 9, SCCH#1 is formed with CCE #1 and CCE #2 as shown in FIG. 11. For thisreason, mapping section 305 maps the response signals to uplink datatransmitted from mobile station 400 to downlink control channels CH #1and CH #2 associated with CCE #1 and CCE #2. This mapping processingwill be described later in detail.

Further, based on the SCCH allocation information received as input fromSCCH allocation section 301, mapping section 305 maps RB allocationinformation symbols to SCCH #1 to SCCH #8 mapped on the frequencydomain. For example, when mapping section 305 receives SCCH #1 from SCCHallocation section 301 as SCCH allocation information for mobile station400, mapping section 305 maps the RB allocation information symbols toSCCH #1.

IFFT section 306 performs an IFFT on the SCCH allocation informationsymbols, RB allocation information symbols and response signals mappedto a plurality of subcarriers, to generate an OFDM symbol, and outputsthe generated OFDM symbol to CP addition section 111.

Meanwhile, in mobile station 400 shown in FIG. 13, FFT section 401performs an FFT on the OFDM symbol after CP removal, to acquire SCCHallocation information symbols, RB allocation information symbols andresponse signals, and outputs them to demultiplexing section 402.

Demultiplexing section 402 demultiplexes the input signals into the SCCHallocation information symbols, the RB allocation information symbolsand response signals, and outputs the SCCH allocation informationsymbols to P/S section 403, the RB allocation information symbols to P/Ssection 206 and the response signals to P/S section 210. Here, based onthe specified result received as input from mapping specifying section406, demultiplexing section 402 demultiplexes the RB allocationinformation symbols and the response signals from the input signal.

P/S section 403 converts a plurality of parallel SCCH allocationinformation symbols received as input from demultiplexing section 402into SCCH allocation information symbols in series, and outputs the SCCHallocation information symbols in series to demodulation section 404.

Demodulation section 404 demodulates the SCCH allocation informationsymbols, and outputs the demodulated SCCH allocation information todecoding section 405.

Decoding section 405 decodes the demodulated SCCH allocationinformation, and outputs the decoded SCCH allocation information tomapping specifying section 406.

Based on the SCCH allocation information received as input from decodingsection 405, mapping specifying section 406 specifies downlink controlchannels to which response signals to uplink data transmitted from themobile station are mapped. For example, when the SCCH allocationinformation for the mobile station is SCCH #1 shown in FIG. 9, SCCH #1is formed with CCE #1 and CCE #2 as shown in FIG. 9, and therefore, asshown in FIG. 11, mapping specifying section 406 specifies CH #1 and CH#2 to be downlink control channels for the mobile station to which theresponse signals are mapped. Then, mapping specifying section 406outputs the specified result to demultiplexing section 402. Thespecifying processing will be described later in detail.

Further, based on the SCCH allocation information received as input fromdecoding section 405, mapping specifying section 406 specifies the SCCHto which the RB allocation information symbols are mapped for the mobilestation. For example, when the SCCH allocation information for a mobilestation is SCCH #1, mapping specifying section 406 specifies SCCH #1 tobe an SCCH for the mobile station to which the RB allocation informationsymbols for the mobile station are mapped. Then, mapping specifyingsection 406 outputs the specified result to demultiplexing section 402.

Demodulation section 208 decodes the demodulated RB allocationinformation, and outputs the decoded RB allocation information totransmission control section 214.

Next, the mapping processing in mapping section 305 in base station 300and the specifying processing in mapping specifying section 406 inmobile station 400 will be explained in detail.

With the present embodiment, mobile station 400 receives the RBallocation information transmitted from base station 300 using SCCH #1to SCCH #8 shown in FIG. 9. Further, base station 300 maps responsesignals to uplink data (ACK signals and NACK signals) to downlinkcontrol channels CH #1 to CH #8, mapped in four frequency bands,subcarriers f1 to f4, f9 to f12, f17 to f20 and f25 to f28 shown in FIG.6, and transmits the response signals to mobile station 400. Further,similar to FIG. 2, spreading section 106 in base station 300 spreads theresponse signal with spreading code having spreading factor 4, andrepetition section 107 repeats the spread response signal withrepetition factor 2. Further, as shown in FIG. 11, the CCEs shown inFIG. 9 and the downlink control channels shown in FIG. 6 are associatedone by one.

Mapping section 305 maps response signals for mobile station 400 to aplurality of downlink control channels that are associated with aplurality of CCEs and that are subject to distributed mapping on thefrequency domain. Mapping section 305 holds association informationbetween SCCHs and CCEs shown in FIG. 9, association information betweenCCEs and downlink control channels shown in FIG. 11, and the downlinkcontrol channel mapping information shown in FIG. 6, and, based onthese, maps the response signals to subcarriers to which downlinkcontrol channels are mapped.

To be more specific, when the SCCH allocation information for mobilestation 400 designates SCCH #1, SCCH #1 is formed with CCE #1 and CCE #2as shown in FIG. 9. For this reason, mapping section 305 maps responsesignals to CH #1 associated with CCE #1 in FIG. 11, that is, mapsresponse signals to subcarriers f1 to f4 and f17 to f20 shown in FIG. 6,and maps response signals to CH #2 associated with CCE #2, that is, mapsresponse signals to subcarriers f9 to f12 and f25 to f28.

Here, in the downlink control channel mapping shown in FIG. 6, downlinkcontrol channels (e.g. CH #1 and CH #2) associated with two consecutivedownlink CCEs in FIG. 9 (e.g. CCE #1 and CCE #2) are mapped to differentfrequency bands in a distributed manner. In other words, the downlinkcontrol channels mapped in a localized manner in identical frequencybands in FIG. 6 correspond to a plurality of nonconsecutive downlinkCCEs at two-CCE intervals in FIG. 9. To be more specific, for example,downlink control channels mapped to subcarriers f1 to f4 shown in FIG. 6in a localized manner are downlink control channels CH #1, CH #3, CH #5and CH #7, and the downlink CCEs associated with those downlink controlchannels are nonconsecutive CCEs at two-CCE intervals, CCE #1, CCE #3,CCE #5 and CCE #7, as shown in FIG. 11.

Consequently, when base station 300 transmits response signals to uplinkdata transmitted from mobile station 400 to which the RB allocationinformation is transmitted using an SCCH formed with a plurality ofconsecutive CCEs, it is possible to prevent response signals from beingmapped concentrated in identical frequency bands. That is, base station300 is able to map response signals over a plurality of frequency bandsin a distributed manner, to transmit the response signals subject todistributed mapping. For example, as described above, when the SCCHallocation information for mobile station 400 designates SCCH #1,mapping section 305 maps response signals to subcarriers f1 to f4 andf17 to f20 shown in FIG. 6, and response signals to subcarriers f9 tof12 and f25 to f28. By this means, response signals are mapped to allsubcarriers f1 to f4, f9 to f12, f17 to f20 and f25 to f28, uniformly,to which downlink control channels are mapped, in a distributed manner.

In this way, mapping section 305 maps response signals to downlinkcontrol channels based on the associations between SCCHs and CCEs shownin FIG. 9, the associations between CCEs and downlink control channelsshown in FIG. 11, and the downlink control channel mapping shown in FIG.6, so that radio transmitting section 112 in base station 300 is able totransmit response signals to mobile station 400 using downlink controlchannels that are associated with downlink CCEs and that are mapped in adistributed manner on the frequency domain.

Likewise, mapping specifying section 406 in mobile station 400 (FIG. 13)holds the association information between SCCHs and CCEs shown in FIG.9, the association information between CCEs and downlink controlchannels shown in FIG. 11 and the downlink control channel mappinginformation shown in FIG. 6, and specifies the downlink control channelsto which response signals for the mobile station are mapped, from theSCCH allocation information received. To be more specific, when mappingspecifying section 406 receives as input SCCH allocation informationshowing that SCCH #1 shown in FIG. 9 is allocated to a mobile stationfrom decoding section 405, based on the associations shown in FIGS. 9and 11, mapping specifying section 406 specifies that the responsesignals for the mobile station are mapped to subcarriers f1 to f4 andf17 to f20, to which downlink control channel CH #1 is mapped and aremapped, to subcarriers f9 to f12 and f25 to f28, to which downlinkcontrol channel CH #2 is mapped, as shown in FIG. 6.

In this way, according to the present embodiment, when one SCCH isformed with a plurality of consecutive downlink CCEs, it is less likelythat response signals concentrate in identical frequency bands and arecode-multiplexed, so that it is possible to map response signals in adistributed manner on the frequency domain. Therefore, according to thepresent embodiment, similar to Embodiment 1, it is possible to maximizethe frequency diversity effect on downlink control channels.

Although a case has been explained with the present embodiment where anSCCH is an example of a control channel formed with a plurality of CCEs,control channels to apply to the present invention is not limited to anSCCH. All control channels formed with a plurality of consecutive CCEsare applicable to the present invention.

Further, similar to Embodiment 2, mapping section 305 in the presentembodiment may map response signals to a plurality of downlink controlchannels mapped in distributed manner on the frequency domain indifferent patterns.

Further, similar to Embodiment 3, mapping section 305 with the presentembodiment may map response signals to a plurality of downlink controlchannels adopting different mapping patterns between neighboring cellsor sectors.

Further, although a case has been explained with the present embodimentwhere SCCH allocation information is transmitted before RB allocationinformation is transmitted in an SCCH, it is not necessary to transmitSCCH allocation information before transmitting RB allocationinformation. For example, the base station includes mobile station IDsthat can identify mobile stations in SCCHs and transmits them, and themobile station decodes all received SCCHs and performs blind detectionas to whether or not there is an SCCH for the mobile station, so that itis possible to make it unnecessary to transmit SCCH allocationinformation before transmitting RB allocation information.

Further, as for the time to switch downlink control channels associatedwith CCEs to a newly allocated SCCH, fixed time may be set up inadvance, or time that changes adaptively may be informed from the basestation to the mobile station using, for example, an SCCH.

Further, when SCCH #1 to SCCH #6 adopt the configurations shown in FIG.14, that is, when SCCH #1 is formed with CCE #1 and CCE #3, SCCH #2 isformed with CCE #5 and CCE #7, SCCH #3 is formed with CCE #2 and CCE #4,SCCH #4 is formed with CCE #6 and CCE #8, SCCH #5 is formed with CCE #1,CCE #3, CCE #5 and CCE #7, and SCCH #6 is formed with CCE #2, CCE #4,CCE #6 and CCE #8, downlink control channels CH #1 to CH #8 may bemapped as shown in FIG. 15. The downlink control channels (e.g. CH #1and CH #3) associated with a plurality of downlink CCEs forming theSCCHs (e.g. CCE #1 and CCE #3 forming SCCH #1) in FIG. 14 are mapped indifferent frequency bands in a distributed manner. Consequently, whenbase station 300 transmits response signals to uplink data transmittedfrom mobile station 400, to which RB allocation information istransmitted, using an SCCH formed with a plurality of CCEs, it ispossible to prevent response signals from being mapped concentrated inidentical frequency bands. That is, as described above, base station 300is able to transmit response signals by mapping the response signals toa plurality of bands in a distributed manner.

Embodiment 5

A case will be explained with the present embodiment where the number ofCCEs to use varies on a per subframe basis.

Studies are underway to change the number of OFDM symbols upon whichCCEs, which forms a downlink control channel (e.g. SCCH) to reportuplink or downlink allocation information, are multiplexed (hereinafterreferred to as “the number of OFDMs for multiplexing”) on a per subframebasis. At that time, the number of OFDMs for multiplexing is reportedfrom the base station to mobile stations using a PCFICH (PhysicalControl Format Indicator Channel). There are more physical resources tomultiplex CCEs upon increasing the number of OFDMs for multiplexing, andtherefore, the number of CCEs to use further increases. For example,when the number of OFDMs for multiplexing is one amongst CCE #1 to CCE#16 shown in FIG. 16, CCE #1 to CCE #4 are multiplexed on one OFDMsymbol, and, when the number of OFDMs for multiplexing is two, CCE #1 toCCE #16 are multiplexed on two OFDM symbols. That is, in the case whereone SCCH is formed with one CCE or a plurality of CCEs, any of CCE #1 toCCE #4 are used when the number of OFDMs for multiplexing is one and anyof CCE #1 to CCE #16 are used when the number of OFDMs for multiplexingis two.

At this time, amongst CCE #1 to CCE #16 shown in FIG. 16, while CCE #1to CCE #4 are used when a plurality of numbers of OFDMs for multiplexing(one or two) are different, CCE #5 to CCE #16 are only used when thenumber of OFDMs for multiplexing is two. That is, CCE #1 to CCE #16 aresorted into CCEs to use between a plurality of different numbers ofOFDMs for multiplexing, and CCEs not to use. Further, CCEs with downlinkcontrol channels for transmitting response signals in downlink areassociated, and the number of CCEs to use increases or decreasesdepending on the number of OFDMs for multiplexing, and accordingly, thenumber of downlink control channels used to transmit response signalsincreases or decreases. That is, similar to CCEs, downlink controlchannels are sorted into downlink control channels to use between aplurality of different numbers of OFDMs for multiplexing, and downlinkcontrol channels not to use.

Here, if the number of OFDMs for multiplexing is one, that is, if CCE #1to CCE #4 shown in FIG. 16 are only used, downlink control channels CH#1 to CH #4 are mapped concentrated in identical frequency bands,subcarriers f1 to f4 and subcarriers f17 to f20, subject to downlinkcontrol channel mapping shown in FIG. 2, for example. For this reason,transmission power varies between frequency bands to which downlinkcontrol channels are mapped (i.e. between four frequency bands ofsubcarriers f1 to f4, f9 to f12, f17 to f20 and f25 to f28 in FIG. 2).Particularly, if response signals concentrate and are code-multiplexedin frequency bands to which downlink control channels CH #1 to CH #4 aremapped, interfering power against other cells increases. Further, ISIincreases in frequency bands in which response signal concentrate andare code-multiplexed.

Then, with the present embodiment, downlink control channels fortransmitting response signals in association with CCEs to use between aplurality of different numbers of OFDMs for multiplexing, are mapped ina distributed manner on the frequency domain.

FIG. 17 shows the configuration of base station 500 according to thepresent embodiment, and FIG. 19 shows the configuration of mobilestation 600 according to the present embodiment. In FIG. 17, the samereference numerals are assigned to the same components in FIG. 12(Embodiment 4), and description thereof will be omitted. Further, inFIG. 19, the same reference numerals are assigned to the same componentsin FIG. 13 (Embodiment 4), and description thereof will be omitted.

In base station 500 shown in FIG. 17, multiplexed OFDM numberdetermination section 501 determines the number of OFDM symbols uponwhich CCEs are multiplexed according to the number of SCCHs that arerequired to report control information on a per subframe basis. To bemore specific, multiplexed OFDM number determination section 501determines increasing the number of OFDMs for multiplexing when thenumber of SCCHs that are required to report control information isgreater. Then, multiplexed OFDM number determination section 501generates multiplexed OFDM number determination information showing thenumber of OFDMs for multiplexing determined, and outputs the generatedmultiplexed OFDM number determination information to encoding section502 and SCCH allocation section 505.

Encoding section 502 encodes the multiplexed OFDM number determinationinformation, and outputs the encoded multiplexed OFDM numberdetermination information to modulation section 503.

Modulation section 503 modulates the encoded multiplexed OFDM numberdetermination information, to generate multiplexed OFDM numberdetermination information symbols, and outputs the multiplexed OFDMnumber determination information symbols to S/P section 504.

S/P section 504 converts the multiplexed OFDM number determinationinformation symbols received as input from modulation section 503 inseries into parallel multiplexed OFDM number determination informationsymbols, and outputs the parallel information symbols to mapping section506.

Based on the multiplexed OFDM number determination information receivedas input from multiplexed OFDM number determination section 501, SCCHallocation section 505 allocates SCCHs to mobile stations. For example,when the number of OFDMs for multiplexing received as input frommultiplexed OFDM number determination section 501 is one, SCCHallocation section 505 allocates SCCHs formed with one CCE or aplurality of CCEs amongst CCE #1 to CCE #4 shown in above FIG. 16, tomobile stations. Meanwhile, when the number of OFDMs for multiplexingreceived as input from multiplexed OFDM number determination section 501is two, SCCH allocation section 505 allocates SCCHs formed with one CCEor a plurality of CCEs amongst CCE #1 to CCE #16 shown in above FIG. 16,to mobile stations.

Mapping section 506 maps the multiplexed OFDM number determinationinformation symbols, the RB allocation information symbols and responsesignals to a plurality of subcarriers forming an OFDM symbol, andoutputs them to IFFT section 507. Here, mapping section 506 mapsresponse signals to downlink control channels CH #1 to CH #16 includingdownlink control channels CH #1 to CH #4, which are mapped in adistributed manner on the frequency domain in association with CCE #1 toCCE #4 to use between a plurality of different numbers of OFDMs formultiplexing, amongst CCE #1 to CCE #16 shown in above FIG. 16. Thismapping processing will be described later in detail.

Further, mapping section 506 maps the multiplexed OFDM numberdetermination information symbols to PCFICHs mapped on the frequencydomain.

IFFT section 507 performs an IFFT on the multiplexed OFDM numberdetermination information symbols, the RB allocation information symbolsand response signals mapped to a plurality of subcarriers, to generatean OFDM symbol, and outputs the generated OFDM symbol to CP additionsection 111.

Downlink control channels for transmitting response signals (e.g.ACK/NACK channels), PCFICHs and CCEs are multiplexed on physicalresources defined in the frequency domain and time domain as shown inFIGS. 18A and 18B, for example. When the number of OFDMs formultiplexing is one, as shown in FIG. 18A, ACK/NACK channels, PCFICHsand CCE #1 to CCE #4 are multiplexed on one OFDM symbol, and when thenumber of OFDMs for multiplexing is two, as shown in FIG. 18B, ACK/NACKchannels, PCFICHs and CCE #1 to CCE #16 are multiplexed on two OFDMsymbols.

Meanwhile, in mobile station 600 shown in FIG. 19, FFT section 601performs an FFT on the OFDM symbol after CP removal, to acquire themultiplexed OFDM number determination information symbols, RB allocationinformation symbols and response signals, and outputs them todemultiplexing section 602.

Demultiplexing section 602 demultiplexer the input signals into themultiplexed OFDM number determination information symbols, the RBallocation information symbols and the response signals, and outputs themultiplexed OFDM number determination information symbols to P/S section603, the RB allocation information symbols to P/S section 206 and theresponse signals to P/S section 210.

P/S section 603 converts the parallel multiplexed OFDM numberdetermination information symbols received as input from demultiplexingsection 602 into the multiplexed OFDM number determination informationsymbols in series, and outputs the multiplexed OFDM number determinationinformation symbols in series to demodulation section 604.

Demodulation section 604 demodulates the multiplexed OFDM numberdetermination information symbols, and outputs the demodulatedmultiplexed OFDM number determination information to decoding section605.

Decoding section 605 decodes the demodulated multiplexed OFDM numberdetermination information, and outputs the decoded multiplexed OFDMnumber determination information to multiplexed OFDM number extractionsection 606.

Multiplexed OFDM number extraction section 606 extracts the number ofOFDMs for multiplexing that is multiplexed from the multiplexed OFDMnumber determination information received as input from decoding section605.

Based on the number of OFDMs for multiplexing received as input frommultiplexed OFDM number extraction section 606, mapping specifyingsection 607 specifies downlink control channels to which responsesignals are mapped and CCEs to use for SCCH allocation. Then, mappingspecifying section 607 outputs the specified result to demultiplexingsection 602. The specifying processing will be described later indetail.

Next, the mapping processing in mapping section 506 in base station 500and the specifying processing in mapping specifying section 607 inmobile station 600 will be explained in detail.

With the present embodiment, as shown in FIG. 16, there are two possiblevalues for the number of OFDMs for multiplexing, one or two. Further,mobile station 600 receives the RB allocation information transmittedfrom base station 500 using SCCHs formed with one CCE or a plurality ofCCEs, amongst CCE #1 to CCE #16 shown in FIG. 16. Further, similar toEmbodiment 4, spreading section 106 in base station 500 spreads theresponse signal with spreading code having spreading factor 4, andrepetition section 107 repeats the spread response signal withrepetition factor 2. However, for ease of explanation, an explanationwill be given to only downlink control channels CH #1 to CH #16 mappedto four frequency bands, subcarriers f1 to f4, f9 to f12, f17 to f20 andf25 to f28, to which response signals are mapped, as shown in FIG. 20,without taking into consideration of repetition. Further, CCE #1 to CCE#16 shown in FIG. 16 and downlink control channels CH #1 to CH #16 shownin FIG. 20 are associated one by one.

Mapping section 506 maps the response signals for mobile station 600 todownlink control channels CH #1 to CH #16 including CH #1 to CH #4 thatare subject to distributed mapping on the frequency domain and that areassociated with CCE #1 to CCE #4 to use between a plurality of differentnumbers of OFDMs for multiplexing amongst CCE #1 to CCE #16 shown inabove FIG. 16.

That is, as shown in FIG. 20, downlink control channel CH #1 is mappedto subcarriers f1 to f4, downlink control channel CH #2 is mapped tosubcarriers f9 to f12, downlink control channel CH #3 is mapped tosubcarriers f17 to f20, and downlink control channel CH #4 is mapped tosubcarriers f25 to f28.

Further, as shown in FIG. 20, downlink control channels CH #5 to CH #16other than downlink control channels CH #1 to CH #4 are mapped to fourfrequency bands, subcarriers f1 to f4, f9 to f12, f17 to f20 and f25 tof28.

Here, in the downlink control channel mapping shown in FIG. 20, downlinkcontrol channels CH #1 to CH #4, which are associated with CCE #1 to CCE#4 to use between a plurality of different numbers of OFDMs formultiplexing (one or two) in FIG. 16, are mapped in a distributed mannerin different bands. In other words, the downlink control channels mappedin a localized manner in identical frequency bands in FIG. 20 are onechannel out of downlink control channels CH #1 to CH #4 associated withCCE #1 to CCE #4 to use between a plurality of different numbers ofOFDMs for multiplexing in FIG. 16, and three channels out of downlinkcontrol channels CH #5 to CH #16 associated with CCE #5 to CCE #16 usedonly when the number of OFDMs for multiplexing is two in FIG. 16. To bemore specific, for example, downlink control channels mapped tosubcarriers f1 to f4 shown in FIG. 20 in a localized manner are downlinkcontrol channels CH #1, CH #5, CH #9 and CH #13. As shown in FIG. 16,downlink CCEs in association with these downlink control channels areCCE #1 to use between a plurality of different numbers of OFDMs formultiplexing (one or two), and CCE #5, CCE #9 and CCE #13, which areused only when the number of OFDMs for multiplexing is two.

Consequently, when base station 500 transmits response signals to uplinkdata transmitted from mobile station 600, transmitted RB allocationinformation using SCCHs formed with CCEs to use between a plurality ofdifferent numbers of OFDMs for multiplexing, it is possible to preventresponse signals from being mapped concentrated in identical frequencybands. That is, base station 500 is able to map response signals over aplurality of frequency bands in a distributed manner, to transmit theresponse signals subject to distributed mapping even when the number ofOFDMs for multiplexing is one. That is, the number of response signalsto code multiplex is the same between frequency bands.

By this means, transmission power in frequency bands to which downlinkcontrol channels for transmitting response signals are mapped changeslittle, and therefore, the effect of averaging transmission powerimproves. That is, it is possible to suppress an increase in part oftransmission power in frequency bands to which downlink control channelsare mapped, in a concentrated manner, so that it is possible to reduceinter-cell interference between neighboring cells. Further, it ispossible to prevent response signals from being mapped concentrated inidentical frequency bands because response signals are mapped in adistributed manner on the frequency domain, so that it is also possibleto reduce ISI between downlink control channels mapped in identicalfrequency bands.

In this way, based on the information about the number of OFDMs formultiplexing shown in FIG. 16 and the downlink control channel mappingshown in FIG. 20, mapping section 506 maps response signals to downlinkcontrol channels. By this means, radio transmitting section 112 in basestation 500 is able to transmit response signals to mobile station 600using downlink control channels mapped in a distributed manner on thefrequency domain in association with downlink CCEs to use between aplurality of different numbers of OFDMs for multiplexing.

Likewise, mapping specifying section 607 in mobile station 600 (FIG. 19)holds the information on the number of OFDMs for multiplexing shown inFIG. 16 and the downlink control channel mapping information shown inFIG. 20, and specifies the downlink control channels to which responsesignals for the mobile station are mapped, from the multiplexed OFDMnumber determination information received. For example, when the numberof OFDMs for multiplexing received as input from multiplexed OFDM numberextraction section 606 is one, mapping specifying section 607 specifiesdownlink control channels to which response signals for the mobilestation are mapped, from downlink control channels CH #1 to CH #4 shownin FIG. 20 in association with CCE #1 to CCE #4 shown in FIG. 16.

In this way, according to the present embodiment, downlink controlchannels in association with CCEs to use between different numbers ofOFDMs for multiplexing are mapped in a distributed manner on thefrequency domain. In this way, it is less likely that response signalsconcentrate in identical frequency bands and code-multiplexed.Therefore, the present embodiment provides the same advantage as inEmbodiment 4. Further, according to the present embodiment, even whenthe number of OFDMs for multiplexing changes on a per subframe basis,transmission power of downlink control channels are averaged between thefrequency bands, so that it is possible to reduce inter-cellinterference between neighboring cells. Further, according to thepresent embodiment, it is possible to reduce ISI between downlinkcontrol channels mapped in identical frequency band.

Although a case has been explained with the present embodiment wherethere are two possible values, one or two, for the number of OFDMs formultiplexing, the present invention may also be implemented where thereare three or more possible values for the number of OFDMs formultiplexing.

Further, although a case has been explained with the present embodimentwhere a plurality of CCEs are sorted into the CCEs to use between aplurality of different numbers of OFDMs for multiplexing, and the CCEsnot to use, a plurality of CCEs may be sorted based on how often theyare used. For example, if the number of OFDMs for multiplexing isbetween one and three, a CCE to use where the number of OFDMs formultiplexing is between one and three is “high” frequency of use, a CCEto use where the number of OFDMs for multiplexing is two or three is“medium” frequency of use, and a CCE to use where the number of OFDMsfor multiplexing is only three is “low” frequency of use. Then, the basestation may map response signals to downlink control channels in adistributed manner on the frequency domain in association with a CCE of“high” frequency of use.

A case has been explained with the present embodiment where the CCEnumbers of CCEs (i.e. CCE #1 to CCE #4 shown in FIG. 16) to use betweena plurality of different numbers of OFDMs for multiplexing areconsecutive. However, the CCE numbers of CCEs to use between a pluralityof different numbers of OFDMs for multiplexing are not limited to beconsecutive. The present invention may also be implemented where the CCEnumbers of CCEs to use between a plurality of different numbers of OFDMsfor multiplexing are nonconsecutive.

Further, although a case has been explained with the present embodimentwhere the CCE numbers and the downlink control channels for transmittingresponse signals are associated, the present invention may also beimplemented in a case where downlink control channels formed with aplurality of CCEs, for example, the SCCH numbers of SCCHs, and downlinkcontrol channels for transmitting response signals are associated.

Further, although a case has been explained with the present embodimentwhere response signals are multiplexed on a plurality of downlinkcontrol channels mapped in different frequency bands in association witha plurality of CCEs to use between a plurality of different numbers ofOFDMs for multiplexing, multiplexing response signals on a plurality ofdownlink control channels mapped in different bands and multiplexingresponse signals on different spreading coding blocks are equivalent.

Further, although a case has been explained with the present embodimentwhere the number of OFDMs for multiplexing is determined according tothe number of SCCHs that are required to report control information,with the present invention, where the number of OFDMs for multiplexingmay be determined according to other control information withoutlimiting to the number of SCCHs. For example, the number of OFDMs formultiplexing may be determined according to the number of multiplexingof ACK/NACK channels that multiplex response signals.

Embodiments of the present invention have been explained.

The present invention may be applicable to mobile stations located neara cell edge. Generally, channel quality is poorer near a cell edge thanin the center of a cell, and a mobile station near a cell edge transmitsuplink data using a low level MCS (Modulation and Coding Scheme). Thatis, a mobile station near a cell edge transmits uplink data using alower coding rate and a modulation scheme of a smaller M-ary modulationnumber than a mobile station near the center of a cell, and therefore,longer uplink data lengths, that is, more consecutive RBs are required.Then, by applying the present invention to a mobile station near a celledge, it is possible to obtain greater frequency diversity effect.

Further, although cases have been explained with the above embodimentsas an example of completely consecutive RBs, the present invention mayalso be implemented by RBs with high consecutiveness even when the RBshave partly nonconsecutive portions.

Further, although cases have been explained with the above embodimentswhere the number of uplink RBs and the number of downlink CCEs areeight, the number of uplink RBs and the number of downlink CCEs are notlimited to eight.

Further, although cases have been explained with the above embodimentsas an example where eight downlink control channels CH #1 to CH #8 aremapped to sixteen subcarriers, subcarriers f1 to f4, f9 to f12, f17 tof20 and f25 to f28, the number of subcarriers and the number of downlinkcontrol channels are not limited to these numbers. For example, as shownin FIG. 21, sixteen downlink control channels CH #1 to CH #16 are mappedto thirty two subcarriers as shown in FIG. 21.

Further, although cases have been explained with the above embodimentsto show only subcarriers to which downlink control channels are mappedin the figures, other control channels or data channels may be mapped tofrequencies besides frequencies to which downlink control channels aremapped.

Further, although cases have been explained with the above embodimentswhere a response signal is spread, a response signal may be mapped to adownlink control channel mapped to frequencies without spreading aresponse signal and transmitted. For example, as shown in FIG. 22, aresponse signal may be mapped to downlink control channels CH #1 to CH#8 in a distributed manner on the frequency domain, without spreading aresponse signal, that is, without code-multiplexing on the samefrequencies.

Further, although cases have been explained with the above embodimentsas examples where spreading factor SF is 4 in spreading section 106 andrepetition factor RF is 2 in repetition section 107, SF and RF are notlimited to these values.

Further, although cases have been explained with the above embodimentsabout the downlink control channel mapping method, the present inventionmay be applicable to uplink control channels. For example, the mobilestation performs the same processing as above base station 100 or 300and the base station performs the same processing as the mobile station200 or 400, so that the present invention may be applicable to uplink.

Further, although cases have been explained with the above embodimentswhere DFTs-FDMA is used as an uplink access scheme, the presentinvention is not limited to DFTs-FDMA, and, the same advantage as abovemay be provided in a communication scheme in which a plurality ofconsecutive RBs are allocated to one mobile station and a communicationscheme in which one control channel is formed from a plurality ofconsecutive CCEs.

Further, although cases have been explained with the above embodimentsas an example where the downlink communication scheme is the OFDMscheme, the downlink communication scheme is not limited in the presentinvention, and the same advantage as above may be provided in acommunication scheme of performing transmission using differentfrequencies.

Further, the downlink control channels for transmitting response signalsused in the explanation of the above embodiments are channels forfeeding back ACK signals or NACK signals for mobile stations. For thisreason, the downlink control channels for transmitting response signalsmay be referred to as “DCCHs (Dedicated Control Channels),” “ACK/NACKchannels,” “response channels” and “HICH (Hybrid ARQ IndicatorChannel).”

Further, although cases have been explained with the above embodimentsabout downlink control channels for mapping response signals, signalsmapped to downlink control channels are not limited to response signals.For example, control signals for reporting a modulation scheme or codingrate upon retransmission, control signals for reporting transmissionpower upon retransmission, control signals for reporting a timetransmission is performed upon retransmission, or control signals forreporting RB allocations upon retransmission are mapped to downlinkcontrol channels.

Further, the RB used in the explanation with the above embodiments maybe other transmission units on the frequency domain, for example, asubcarrier block and a sub-band.

A base station, a mobile station and a subcarrier may be referred to asa “Node B,” a “UE,” and a “tone,” respectively. A CP may be referred toas a “guard interval (GI).

Further, the error detection method is not limited to a CRC check.

Further, the transform method between the frequency domain and the timedomain is not limited to the IFFT and FFT.

Moreover, although cases have been described with the embodiments abovewhere the present invention is configured by hardware, the presentinvention may be implemented by software.

Each function block employed in the description of the aforementionedembodiment may typically be implemented as an LSI constituted by anintegrated circuit. These may be individual chips or partially ortotally contained on a single chip. “LSI” is adopted here but this mayalso be referred to as “IC,” “system LSI,” “super LSI” or “ultra LSI”depending on differing extents of integration.

Further, the method of circuit integration is not limited to LSPs, andimplementation using dedicated circuitry or general purpose processorsis also possible. After LSI manufacture, utilization of an FPGA (FieldProgrammable Gate Array) or a reconfigurable processor where connectionsand settings of circuit cells within an LSI can be reconfigured is alsopossible.

Further, if integrated circuit technology comes out to replace LSI's asa result of the advancement of semiconductor technology or a derivativeother technology, it is naturally also possible to carry out functionblock integration using this technology. Application of biotechnology isalso possible.

The disclosures of Japanese Patent Application No. 2007-077502, filed onMar. 23, 2007, Japanese Patent Application No. 2007-120853, filed on May1, 2007, and Japanese Patent Application No. 2007-211104, filed on Aug.13, 2007, including the specifications, drawings and abstracts, areincorporated herein by reference in their entirety.

INDUSTRIAL APPLICABILITY

The present invention is applicable to, for example, mobilecommunication systems.

What is claimed is:
 1. A mobile station comprising: a receiverconfigured to receive, from a base station, allocation informationindicating one or a plurality of allocated resource block(s) of uplinkwhich are consecutive in a frequency domain; and a processor configuredto determine, based on the allocation information, one of the resourcesof downlink, to which an acknowledgement (ACK) or negativeacknowledgement (NACK) signal is distributively mapped onto a pluralityof resource elements in subcarrier groups, wherein the subcarrierresources within a subcarrier group are consecutive in frequency domainand nonconsecutive in the frequency domain among the subcarrier groups.2. The mobile station of claim 1, wherein indices of the plurality ofthe consecutive resource blocks are respectively associated with aplurality of the resources of downlink which are different in thefrequency domain, and wherein the processor is configured to determinethe resources of downlink to which the ACK or NACK signal for the uplinkdata is mapped from the index of the associated resource block withinthe indices of the plurality of consecutive resource blocks.
 3. Themobile station of claim 1, further comprising a transmitter configuredto transmit data using the allocated resource block based on theallocation information.
 4. The mobile station of claim 1, wherein theACK or NACK signal is carried on a hybrid automatic repeat request (ARQ)indicator channel (HICH) from the base station.
 5. The mobile station ofclaim 1, wherein the ACK or NACK signal is spread in the base station,and the spread ACK or NACK signal is mapped to the resource.
 6. Themobile station of claim 1, wherein a plurality of the same ACK or NACKsignals are generated with a repetition in the base station, and theplurality of the same ACK or NACK signals are mapped to a plurality ofrespective resources.
 7. The mobile station of claim 1, wherein aplurality of the ACK or NACK signals are mapped to the resource withcode-multiplexed.
 8. A method in a mobile station comprising: receiving,from a base station, allocation information indicating one or aplurality of allocated resource block(s) of uplink which are consecutivein a frequency domain; and using a processor to determine, based on theallocation information, one of the resources of downlink, to which anacknowledgement (ACK) or negative acknowledgement (NACK) signal isdistributively mapped onto a plurality of resource elements insubcarrier groups, wherein the subcarrier resources within a subcarriergroup are consecutive in frequency domain and nonconsecutive in thefrequency domain among the subcarrier groups.
 9. The method of claim 8,wherein indices of the plurality of the consecutive resource blocks arerespectively associated with a plurality of the resources of downlinkwhich are different in the frequency domain, and wherein the processoris configured to determine the resources of downlink to which the ACK orNACK signal for the uplink data is mapped from the index of theassociated resource block within the indices of the plurality ofconsecutive resource blocks.
 10. The method of claim 8, furthercomprising a transmitting data using the allocated resource block basedon the allocation information.
 11. The method of claim 8, wherein theACK or NACK signal is carried on a hybrid automatic repeat request (ARQ)indicator channel (HICH) from the base station.
 12. The method of claim8, wherein the ACK or NACK signal is spread in the base station, and thespread ACK or NACK signal is mapped to the resource.
 13. The method ofclaim 8, wherein a plurality of the same ACK or NACK signals aregenerated with a repetition in the base station, and the plurality ofthe same ACK or NACK signals are mapped to a plurality of respectiveresources.
 14. The method of claim 8, wherein a plurality of the ACK orNACK signals are mapped to the resource with code-multiplexed.
 15. Abase station apparatus comprising: a processor configured to: allocate,to a mobile station, a plurality of uplink resource blocks, the resourceblocks being consecutive in a frequency domain; distributively map anacknowledgement (ACK) or negative acknowledgement (NACK) signalassociated with data received on one or more of the plurality of uplinkresource blocks onto a plurality of resource elements in subcarriergroups, wherein the subcarrier resources within a subcarrier group areconsecutive in frequency domain and nonconsecutive in frequency domainamong subcarrier groups; a transmitter configured to transmit the mappedACK or NACK signal to the mobile station.
 16. The base station of claim15, wherein indices of the plurality of the consecutive resource blocksare respectively associated with a plurality of the resources ofdownlink which are different in a frequency domain, and wherein theprocessor is configured to determine the resources of downlink to whichthe ACK or NACK signal for the uplink data is mapped from the index ofthe associated resource block within the indices of the plurality ofconsecutive resource blocks.
 17. The base station of claim 15, thetransmitter is further configured to transmit allocation informationindicating the allocated resource blocks to the mobile station.
 18. Thebase station of claim 15, the processor is configured to spread the ACKor NACK signal, wherein the processor is configured to map the spreadACK or NACK signal to the resource.
 19. The base station of claim 15,the processor is further configured to generate a plurality of the sameACK or NACK signal with a repetition, and wherein the processor isfurther configured to map the plurality of the same ACK or NACK signalsto a plurality of resources distributed in the frequency domain,respectively.
 20. The base station of claim 15, wherein the processor isconfigured to map a plurality of the ACK or NACK signals to the resourcewith code-multiplexing.
 21. A method in a base station apparatuscomprising: using a processor configured to: allocate, to a mobilestation, a plurality of uplink resource blocks, the resource blocksbeing consecutive in a frequency domain; distributively map anacknowledgement (ACK) or negative acknowledgement (NACK) signalassociated with data received on one or more of the plurality of uplinkresource blocks onto a plurality of resource elements in subcarriergroups, wherein the subcarrier resources within a subcarrier group areconsecutive in frequency domain and nonconsecutive in frequency domainamong the subcarrier groups; transmitting the mapped ACK or NACK signalto the mobile station.
 22. The method of claim 21, wherein indices ofthe plurality of the consecutive resource blocks are respectivelyassociated with a plurality of the resources of downlink which aredifferent in a frequency domain, and further comprising determining theresources of downlink to which the ACK or NACK signal for the uplinkdata is mapped from the index of the associated resource block withinthe indices of the plurality of consecutive resource blocks.
 23. Themethod of claim 21, further comprising transmitting allocationinformation indicating the allocated resource blocks to the mobilestation.
 24. The method of claim 21, further comprising spreading theACK or NACK signal and mapping the spread ACK or NACK signal to theresource.
 25. The method of claim 21, further comprising generating aplurality of the same ACK or NACK signal with a repetition, and mappingthe plurality of the same ACK or NACK signals to a plurality ofresources distributed in the frequency domain, respectively.
 26. Themethod of claim 21, further comprising mapping a plurality of the ACK orNACK signals to the resource with code-multiplexing.